Light fixtures creating various effects are getting more and more used in the entertainment industry in order to create various light effects and mood lighting in connection with live shows, TV shows, sport events and/or as a part of architectural installation. Typically entertainment light fixtures create a light beam having a beam width and a divergence and can for instance be wash/flood fixtures creating a relatively wide light beam with a uniform light distribution with a soft edge or it can be profile fixtures adapted to project images onto a target surface. It is common to incorporate mid air light effects into light shows. Mid air effects are created by creating a well-defined light beam which is partially scattered by haze or smoke particle in the air whereby the audience can see the light beam in the air. The mid air light beams are often created in the head of a moving head light fixture where the head is rotatably connected to a yoke which is rotatably connected to a base and the light beam can as a consequence be moved around in the air. Today there are a number of different products (e.g. The MAC 250 Beam™ or the MAC 2000 Beam™ provided by Martin Professional A/S) which are capable of providing such light beams and many of these can create light beams with variable beam divergence and/or collimated light beams having variable beam diameter.
US2010/0103677 discloses a theatre lighting apparatus comprising a base, a communications port, a processor, a memory, and a lamp housing. The lamp housing includes a lamp, a reflector, an output lens, a motor, and a homogenizing lens. The homogenizing lens comprises a plurality of radically arranged lenticular lenses, and a processor programmed to enable a motor to vary a position of the homogenizing lens in relation to a position of the output lens. The homogenizing lens may be comprised of a first half and a second half, each of which may have a plurality of radically arranged lenticular lenses. The lightning apparatus comprises also a prism apparatus positioned between the light source and the output lens. The prism apparatus is constructed of a plurality of prisms mounted to a substrate. In operation, incoming light rays pass through the substrate and through the base of each prism where a first portion of light rays is refracted into a first direction exiting from one side of the prisms, and a second portion of light rays is refracted into a second direction exiting from another side of the prism. The prism apparatus is attached to a rotation motor capable of rotating the prism apparatus about its center, and the prism apparatus and rotation motor are attached to a lead screw and driving motor so the prism apparatus can be transitioned into a light beam. The combination of the prism apparatus and a polymer fresnel front lens results in two substantially separate exiting beams of light (referred to as twin beams). The prism apparatus is also connected to a displacement motor capable of displacing the prism apparatus in relation to the front lens. The angular deviation of the two separate beams of light can hereby be controlled. The twin beams are dependent on each other, since they primarily are created by the prism apparatus and the characteristics (e.g. intensity, color, divergence, size) of the twin beam can thus substantially the same and cannot be controlled independently.